Obesity is one of the most common medical problems in the United States and other developed countries and a risk factor for other illnesses, such as hypertension, diabetes, degenerative arthritis and myocardial infarction. Weight loss medications may be appropriate for use in selected patients who are obese or who are overweight with co-morbid conditions.
One measure for defining obesity is known as a body mass index (BMI), which is weight in kilograms divided by height in meters squared. A BMI of 18.5 to 24.9 is generally classified as normal, a BMI of 25.0 to 29.9 is generally classified as overweight and a BMI of 30 or greater is generally classified as obese. Alternatively, obesity may be defined as the top percentile, such as 15 percent, of a population's weight for a given height. Such definitions of obesity, however, are not a measure of body composition and different people may have higher or lower levels of body fat or muscle mass for their height. Nevertheless, these definitions of obesity are useful characterizations for general populations of people.
The goal of obesity treatment is to exert a negative energy balance on the system by reducing energy input or increasing energy output, or both. Obesity is caused by a constellation of factors including, but not limited to, excessive energy intake (food), insufficient energy output (exercise), low resting metabolic rate, genetic predisposition, low fat oxidation rate, low sympathetic activity and high plasma leptin level. These factors may also have several causes. For example, a low resting metabolic rate may be due to genetic variation involving sympathetic activity, thyroid activity, β3-receptor sensitivity, and adenosine triphosphatase enzyme activity. Genetic factors may include a mutation in the gene coding for the β3-adrenergic receptor causing low β3-adrenergic activity which promotes obesity by slowing lipolysis and causing retention of lipids in fat cells. Moreover, as weight is lost by restricted energy intake, fat cells shrink, reducing expression of leptin, a product of the ob gene. As leptin levels fall, metabolic rate decreases, and appetite increases, thereby generally impeding further weight loss. Thus, obesity control medications are often formulated to reduce energy intake or suppress appetite, increase energy output or decrease the absorption of nutrients by various different approaches.
Despite the current approaches for the treatment or prevention of obesity, there remains a need in the art for improved compositions and treatments for obesity.